In the period from 1962 to 1967, the Department of Nutrition at the Harvard School of Public Health, in conjunction with the Department of Social Medicine at Trinity College, Dublin, examined six groups of men of Irish origin for the then recognized risk factors for coronary heart disease. The two basic groups consisted of pairs of brothers, one of whom had emigrated to Boston and the other remained in Ireland. The third group consisted of Boston-born Irishmen, both of whose parents had emigrated to the United States while the remaining three groups consisted of Irishmen who had not emigrated, selected from two urban and one rural universes. For each subject a dietary history, a history of smoking and of alcohol consumption and an exercise questionnaire were obtained. Anthropometric measurements, a 12-lead electrocardiogram and total serum cholesterol were also obtained. We propose to regain contact with these subjects and to ascertain the cause of death of those who died, and the health status of the survivors. We will thereby be able to compare the risk profile formed from the original data to the current morbidity and mortality status while holding genetic factors in balance. We also plan to maintain contact with our subjects, registering the causes of their deaths as they occur, and will reanalyze the data once more in ten years' time. To increase the value of the follow-up of te current survivors, we plan to measure their current levels of the risk factors previously measured, and in addition to measure HDL-cholesterol. Thus, when analyzing the status of the subjects, we will take into account the levels of risk factors measured 15 years apart. In addition, this study will enable us to follow the dietary, smoking, drinking and exercise patterns of these subjects as they age.